In the heart of the green forest grew a huge tree, which everyone called the Oak House. Among the rustling leaves lived the cheerful squirrel Pusia. Every morning, Pusia jumped from branch to branch and laughed at the sun. Her best friend was Felek the hedgehog, who always carried a little red rucksack with him. One day, when Fluffy and Felek were playing hide and seek, Fluffy noticed something strange under the bark of an old oak tree. It was a small silver handle that she had never seen before. - Felek! Come quickly! - she called out excitedly. Felek trotted towards her cautiously, as he didn't want to lose any needles from his back. - What's that? - He asked, looking at the door handle. - I don't know... Maybe it's a secret door to a world of hidden treasures? - whispered Fluffy with sparkling eyes. As they carefully touched the handle, they heard a quiet click.... And then...